Leaking Electrolyte Surface Mount Electrolytic Capacitors SM

[Wild_Bill]

Much aggravation has been caused by surface mount electrolytic caps that
develop leaks, leaking the electrolyte onto the circuit boards and creating
almost countless faults in a lot of consumer grade electronic gear, and a
large number of camcorders.

Spotting electrolytics that develop external leaks isn't too difficult with
just a good lighting source, in some cases.
In a SONY VCR that I examined recently, when the head amp cover was removed,
it was fairly obvious that the SMT caps were leaky.

Around the plastic base of the caps, there were dark speckles under the
mask. The mask is a protective coating that's placed on the bare board after
the etching is completed, and consists of a very thin layer of translucent
sort-of paint, essentially.

When the electrolyte gets on the circuit board, it can creep under the mask,
and since it's acidic, it can begin to dissolve the copper traces lying
under the mask. This was what had caused the dark speckles that were visible
thru the mask, around the bases of the caps in the head amp.
For very fine circuit traces, the acid can cause enough deterioration of the
traces to cause interrupted paths, or open circuits, but can also in effect
turn the copper traces into resistors.
Traces under and near the cap bases should be closely examined for
deterioration.

To accurately assess the reliability of a circuit board with electrolyte
damage, you will need a finely tuned, recently calibrated crystal ball.

The eletrolyte leakage may also be evident on the caps themselves, near the
bottoms, below the crimp. The acid can attack the aluminum canister that
makes up the covers of the caps, and in the case of the leaky caps in the
head amp, the bottom edges of some of the aluminum cans were noticeably
discolored from the reaction of the acid on the aluminum.

The acid in the electrolyte can also cause solder to have a dark color with
a flat or dull appearance.

In cases where the electrolyte leakage is very limited, leakage can be
verified by touching a hot soldering iron tip to the caps leads/solder pads,
and detecting a fishy smell.

There are many accounts of symptoms/problems and repairs of equipment with
failed, leaky surface mount caps in the archives of SER.

--
Cheers,
WB
..............

 

[Meat Plow]

On Tue, 23 Jun 2009 09:01:03 -0400, "Wild_Bill"
<wb_wildbill@XSPAMyahoo.com>wrote:

<snip>

There are many accounts of symptoms/problems and repairs of equipment with
failed, leaky surface mount caps in the archives of SER.

Any recommendations for a 7 year old Sony miniDV touch screen
Nightshot palmcorder with a failed CCD? Playback is ok. I've given it
a good visual and didn't spot anything obvious. A few years before the
CCD failed I repaired a bad connection on the LCD display that
manifested itself in the form of one missing color.

 

[msg]

Wild_Bill wrote:

<snip>

There are many accounts of symptoms/problems and repairs of equipment
with failed, leaky surface mount caps in the archives of SER.

What datecode range is most suspect? What is the earliest date when
this became a widespread problem? Is it yet another example of the
counterfeit chinese electrolyte issue?

Michael

 

[Wild_Bill]

I haven't been actively involved in consumer electronics servicing for about
a decade, so I don't know first hand what the present general failure rate
is.

None of this low grade equipment is intended to last long, so there will be
more failures. Poor designs, heat and ripple currents of SMPS will ensure
that there are short lived appliances and electronic gear in the years to
come.

Arm yourself with a good ESR tester like the Bob Parker design if you expect
to have a chance of repairing any electronic equipment.
Having an analyzer like Sencore's Z-Meters can also be useful for in-circuit
checks and evaluation of numerous other components.

No one knows what the reliability will be on their next order of capacitors
they receive, even without a huge conspiracy to steal and counterfeit
electrolyte formulas, so prepare.
With the majority of equipment being built to the lowest price point,
manufacturers are likely to buy whatever's on sale this week.

IMO, it's probably best to buy parts like electrolytics from a supplier that
buys direct and has a fairly fast inventory turnover, like DigiKey.
To have some idea of what you're receiving, test your components when you
receive them, and avoid buying large quantities of electrolytics if they'll
just sit in a drawer for a year or more.

You might already know that there are date codes on some of the better
brands of electrolytics (the usual type with wrappers), so when you see old
date codes on new parts, it's time to get a different supplier.

--
Cheers,
WB
..............


"msg" <msg@_cybertheque.org_> wrote in message
news:5fadnR058qU_dt3XnZ2dnUVZ_qOdnZ2d@posted.cpinternet...

Wild_Bill wrote:

snip

There are many accounts of symptoms/problems and repairs of equipment
with failed, leaky surface mount caps in the archives of SER.

What datecode range is most suspect? What is the earliest date when
this became a widespread problem? Is it yet another example of the
counterfeit chinese electrolyte issue?

Michael

 

[Adrian Glaubitz]

Hi,

msg wrote:

Wild_Bill wrote:

snip

There are many accounts of symptoms/problems and repairs of equipment
with failed, leaky surface mount caps in the archives of SER.

What datecode range is most suspect? What is the earliest date when
this became a widespread problem?

From my humble experience, mostly camcorders made in the early to mid
90es are affected. I know from Sony Video8-corders from the 80es which
still work like a charm but know several from the 90es which are
completely failing. I haven't spotted the problem in later models
manufactured around 1998/1999. I have still an 1991 Sony CCD-F355E where
I want to replace all caps and get it back working just for the sake of
repairing it .

PS: I suggest using an ESR-meter to check the caps which a suspect.

Adrian

 

[John Robertson]

Wild_Bill wrote:

Much aggravation has been caused by surface mount electrolytic caps that
develop leaks, leaking the electrolyte onto the circuit boards and
creating almost countless faults in a lot of consumer grade electronic
gear, and a large number of camcorders.

Spotting electrolytics that develop external leaks isn't too difficult
with just a good lighting source, in some cases.
In a SONY VCR that I examined recently, when the head amp cover was
removed, it was fairly obvious that the SMT caps were leaky.

Around the plastic base of the caps, there were dark speckles under the
mask. The mask is a protective coating that's placed on the bare board
after the etching is completed, and consists of a very thin layer of
translucent sort-of paint, essentially.

When the electrolyte gets on the circuit board, it can creep under the
mask, and since it's acidic, it can begin to dissolve the copper traces
lying under the mask. This was what had caused the dark speckles that
were visible thru the mask, around the bases of the caps in the head amp.
For very fine circuit traces, the acid can cause enough deterioration of
the traces to cause interrupted paths, or open circuits, but can also in
effect turn the copper traces into resistors.
Traces under and near the cap bases should be closely examined for
deterioration.

To accurately assess the reliability of a circuit board with electrolyte
damage, you will need a finely tuned, recently calibrated crystal ball.

The eletrolyte leakage may also be evident on the caps themselves, near
the bottoms, below the crimp. The acid can attack the aluminum canister
that makes up the covers of the caps, and in the case of the leaky caps
in the head amp, the bottom edges of some of the aluminum cans were
noticeably discolored from the reaction of the acid on the aluminum.

The acid in the electrolyte can also cause solder to have a dark color
with a flat or dull appearance.

In cases where the electrolyte leakage is very limited, leakage can be
verified by touching a hot soldering iron tip to the caps leads/solder
pads, and detecting a fishy smell.

There are many accounts of symptoms/problems and repairs of equipment
with failed, leaky surface mount caps in the archives of SER.

--
Cheers,
WB
..............

Is it (what leaks from the capacitors) an acid or an alkaline? The
difference is important to the method used to neutralize the leakage.

For an Alkaline leakage (batteries and possibly capacitors) you need to
use a mild acid such as white vinegar or possibly CLR (not corrosive to
copper).

For an acid leakage you need to use a base such as baking powder.

Using the wrong neutralizing agent will only exacerbate the problem!

John :-#)#
--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

 

[JW]

On Wed, 24 Jun 2009 06:09:55 GMT John Robertson <spam@flippers.com> wrote
in Message id: <Tqj0m.33471$PH1.11952@edtnps82>:

Is it (what leaks from the capacitors) an acid or an alkaline? The
difference is important to the method used to neutralize the leakage.

For an Alkaline leakage (batteries and possibly capacitors) you need to
use a mild acid such as white vinegar or possibly CLR (not corrosive to
copper).

For an acid leakage you need to use a base such as baking powder.

Using the wrong neutralizing agent will only exacerbate the problem!

From my experience fixing a number of Tek TDS scopes, a good method is a
wash of Simple Green cleaner using a brush to scrub the boards, followed
by another wash/scrubbing of 99% alcohol.

 

[whit3rd]

On Jun 23, 6:01 am, "Wild_Bill" <wb_wildb...@XSPAMyahoo.com> wrote:

Much aggravation has been caused by surface mount electrolytic caps that
develop leaks, leaking the electrolyte onto the circuit boards and creating
almost countless faults in a lot of consumer grade electronic gear, and a
large number of camcorders.

And Macintosh IIci computer boards; many of these from the early

nineties had high-fault-rate capacitors.

The acid in the electrolyte can also cause solder to have a dark color with
a flat or dull appearance.

In cases where the electrolyte leakage is very limited, leakage can be
verified by touching a hot soldering iron tip to the caps leads/solder pads,
and detecting a fishy smell.

There are many accounts of symptoms/problems and repairs of equipment with
failed, leaky surface mount caps in the archives of SER.

The problem is, there's only one solution: replace all those surface
mount
capacitors. It can take a lot of time, isn't always worth the effort.

Once you see leakage, there's no point in testing (so the ESR is good;
so
what? you still gotta replace or acid will kill adjacent parts) or
cleaning (the
reservoir of corrosive goo is still sitting there next to the spill)
or even
determining which units have failed (there's nine leaks, fourteen
capacitors;
don't tell me I should just trust the five that didn't leak yet).
You have to commit to wholesale component removal and replacement.

I like heat/lift-with-scalpel technique, others may prefer pliers and
wick.

 

[Wild_Bill]

I expect that you're correct John. Treating/rinsing the location of the base
of the leaking capacitor is likely a good practice, but I don't know how
effective it would be at reducing the attack taking place under the solder
mask, such as what was observed in the head amp circuit of the VCR I just
looked at.
The 11 leaking caps in an area of about 4 square inches can cause a lot of
damage.

I believe the electrolyte leakage I've seen on circuit boards has been
acidic, but it's been a long time since I've done any in-depth study of
caps.
Capacitor electrolyte formulas are said to be closely guarded secrets, but
some references are suggested below.

I associate blue-green crystalline material with salt/alkali contact with
copper (although I don't know this indication to be a scientific result).
Leakage damage from electrolytics that I've seen causes the blackening of
metals (solder, copper or tin plating on component leads).

I have some leaky caps presently, but don't have any litmus or pH test
strips to test them with.

From freepatents: The operating electrolyte is composed of a quaternary
ammonium salt of a carboxyl acid, of an additive of the salt-forming
carboxyl acid and of ?-butyrolactone as a solvent.
An electrolyte composition for electrolytic capacitors consisting
essentially of a salt of a slilcotungstatic or silicomolybdic acid in a
polar organic solvent and having a pH of from about 5.0 to about 7.2

From Wikipedia: Electrolytic Capacitor - Electrolyte: The weak acids are
usually organic acid (glacial acetic acid, lactic acid, propionic acid,
butyric acid, crotonic acid, acrylic acid, phenol, cresol, etc.) or boric
acid. The salts employed are often ammonium or metal salts of organic acids
(ammonium acetate, ammonium citrate,
aluminium acetate, calcium lactate, ammonium oxalate, etc.) or weak
inorganic acids (sodium perborate, trisodium phosphate, etc.).
Solvent-based electrolytes may be based on organic hydroxyl alkyl amines
(monoethanolamine, diethanolamine, triethanolamine,...) or polyols
(diethylene glycol, glycerol, etc.).
http://en.wikipedia.org/wiki/Electrolytic_capacitor

Chemistry acid-base relationship
Solutions with a pH of seven (7) are said to be neutral, while those with pH
values below seven (7) are defined as acidic and those above pH of seven (7)
as being basic.
A base is also often referred to as an alkali if OH ions are involved.

When utilizing acids for rust removal or other tasks, baking soda is useful
for neutralizing those acids.

--
Cheers,
WB
..............


"John Robertson" <spam@flippers.com> wrote in message
news:Tqj0m.33471$PH1.11952@edtnps82...

Is it (what leaks from the capacitors) an acid or an alkaline? The
difference is important to the method used to neutralize the leakage.

For an Alkaline leakage (batteries and possibly capacitors) you need to
use a mild acid such as white vinegar or possibly CLR (not corrosive to
copper).

For an acid leakage you need to use a base such as baking powder.

Using the wrong neutralizing agent will only exacerbate the problem!

John :-#)#
--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

 

[Wild_Bill]

There aren't many practical approaches to replacing quantities of leaking
surface mount capacitors, other than some type of hot tweezer-type tool.

There are various styles that essentially perform the same function.. to
heat both terminals of the device simultaneously, with tips that contact the
terminals, or with non-contact hot air nozzles.

That's not to say that it can't be done with basic tools, but servicing
electronic gear on a regular basis requires better equipment.

--
Cheers,
WB
..............

"whit3rd" <whit3rd@gmail.com> wrote in message
news:d769f4cc-fcca-485c-97fa-9c183e9dab5e@o36g2000vbi.googlegroups.com...

And Macintosh IIci computer boards; many of these from the early

nineties had high-fault-rate capacitors.

The problem is, there's only one solution: replace all those surface
mount
capacitors. It can take a lot of time, isn't always worth the effort.

Once you see leakage, there's no point in testing (so the ESR is good;
so
what? you still gotta replace or acid will kill adjacent parts) or
cleaning (the
reservoir of corrosive goo is still sitting there next to the spill)
or even
determining which units have failed (there's nine leaks, fourteen
capacitors;
don't tell me I should just trust the five that didn't leak yet).
You have to commit to wholesale component removal and replacement.

I like heat/lift-with-scalpel technique, others may prefer pliers and
wick.